In a conventional vacuum processing apparatus such as a CVD illustrated in FIG. 1 of the accompanying drawings, one or more substrates A are mounted on the surface of a substrate holder B which is disposed in a vacuum chamber C, and is intended to be rotated by a motor D via a rotation transmitting mechanism E. Around the substrate holder B there is provided an earth shield F which is electrically isolated from the substrate holder B by an insulator member G. The substrate holder B is supplied with DC or RF power from a DC or RF power feeder H which may be or a rotating contact type, a capacitor coupling type or the like. Vacuum seal assembly I is provided on the opening of the chamber wall for preventing a rotating shaft and vacuum seal from vibrating during operation of the substrate holder B. The vacuum rotation seal assembly I may comprise O ring seal, Wilson's seal or magnetic fluid seal. The substrate holder B is provided with either or both of a heater or cooling channel into which a power or cooling water is fed by feeding means J such as a rotary joint.
FIG. 2 illustrates an other conventional CVD apparatus in which the same reference characters are used to designate the components corresponding to those in FIG. 1, and a heating mechanism K is separated from the substrate holder B and is secured to the vacuum chamber C.
In the conventional CVD apparatus as shown in FIG. 1 or 2, a plasma is produced in the vacuum chamber by applying suitable RF power to the substrate holder to generate a glow discharge in the vacuum chamber. In order to vary DC bias to be effectively generated at the surface of the substrate (this DC bias to be generated at the surface of the substrate is strictly more or less different from that to be generated at the surface of the substrate holder, but it is assumed herein that the former is the same as the latter), the RF power itself should be controlled, for example, by providing a mechanism (for example, a capacitor, a coil, a resistor or the like) for varying an impedance in the whole substrate holder mechanism in the RF power transmitting circuit. For the DC or RF power feeding mechanism, there should be used means for introducing the power into the rotating mechanism, and thus this leads to difficulty in maintenance or checking. Further, since the capacitor, coil or resistor to be used for varying the impedance have variable characteristics, it is difficult to make a fine adjustment of the DC bias.
Where the conventional apparatus shown in FIG. 1 or 2 is employed for forming a thin film on the substrate or etching the substrate, in the apparatus illustrated in FIG. 1, a film forming material, a reactive gas or the like may be adhered and deposited not only on the surface of the substrate holder, but also on the whole surface of the earth shield and the chamber wall, and in the case of the apparatus illustrated in FIG. 2 such film forming material or reactive gas may be adhered and deposited on the back side of the substrate holder and the surface of the heater assembly. Cleaning of the portions contaminated by such film forming material or reactive gas becomes troublesome.
In the case of the apparatus shown in FIG. 1, even if the cleaning of the contaminated portions is carried out by a plasma which is generated by introducing a suitable reactive gas or inert gas into the vacuum chamber and applying RF or DC power to the substrate holder, the surface of the substrate holder and the portions fully exposed to the plasma may be cleaned, but it is difficult to clean down the portions which are not exposed and not fully exposed to the plasma.
Furthermore, in the apparatus illustrated in FIG. 1, since the substrate holder :s rotated together with the earth shield, the weight of the components to be rotated becomes heavy and then it is necessary to use a motor having a larger rotating torque. Complication of the substrate holder and the feeding means for the heater power and the cooling water can not be avoided, and the removal or maintenance of these components become troublesome.
It is, therefore, an object of the present invention to provide a vacuum processing method in which the drawbacks of the above-mentioned conventional system can be overcome and a DC bias to be applied to substrates can be mechanically and easily controlled with excellent reproducibility.
Another object of the present invention is to provide a vacuum processing apparatus in which the drawbacks of the above-mentioned conventional system can be overcome and a DC bias to be applied to substrates can be mechanically and easily controlled with excellent reproducibility.
Still another object of the present invention is to provide a method of cleaning substrate holder or susceptor and other components in a vacuum chamber, in which the susceptor and other components can be easily cleaned with maintaining a required evacuated condition in the vacuum chamber.
Still another object of the present invention is to provide a vacuum processing apparatus in which the susceptor and other components in the vacuum chamber can be easily cleaned with maintaining required evacuated condition and a desired processing performance in the vacuum chamber.
A further object of the present invention is to provide a vacuum processing apparatus which comprises a substrate-electrode mechanism which is functionally excellent and has no above-mentioned drawbacks of the conventional system.
A still further object of the present invention is to provide a CVD apparatus in which the construction can be simplified and an excellent function can be obtained.